AAR Slid Flat Tire Test Results

C C I B S E M I N A R

C H I C A G O, I L

7 / 2 8 / 1 5

Initial Assumption and Test Methodology Assumption: A flat spot (slid flat) does not significantly affect the durability of intermodal tires

Tested tires oBias and Radial tires oNew and Retread tires

Test Methodology oShearography – Verify good test samples on retread tires oSlid Flat Generation – CSX NWOH Terminal oFMVSS 119 – DOT endurance testing oCleat Testing – tires run to complete failure oDetermination of durability indices oDetermination of road pressure data (wear information) oDetermination of rolling resistance

Testing Methodology Shearography – imaging of tire section pre and post testing to identify and eliminate internal anomalies from test samples

Shearography (e.g. Bias-Retread)

Before Slid Flat

After Slid Flat

After 47 hours

Slid Flat Generation (CSX Terminal, NWOH)

Testing Methodology

• FMVSS 119

• Tire durability / endurance testing

• Multi-step process to simulate speed and load

• Step 1 – 85% max load for 7 hours

• Step 2 – 90% of max load for 16 hours

• Step 3 – 100% of max load for 24 hours

• Followed by “Cleat Test” – tires run to complete failure

Slid Flat Tire Samples

Tire Group

Avg. Tread Depth

(32nds)

Avg. Slid Flat

Depth (32nds)

Avg. Tread

Depth at Flat Spot (32nds)

Avg. Slid Flat %

Bia New 13 9 4 71Radial New 14 10 4 69Bias Retread 10 6 4 62Radia Retread 11 7 4 62

No Statistically Significant Effect of Slid Flat on Durability of any Tire Group

Bias retreads have 17% less durability bias new. Radial retreads have 13% less durability than radial new. Bias tires have about 40% less durability than radial tires

Slid Flat Pressure Footprint Tire footprint pressure – indication of tire wear

Effect of Slid Flat on Rolling Resistance

Conclusions

Slid flat condition showed no statistically significant effect on tire durability.

Footprint pressure indicates flat spots can wear less quickly than the rest of the tire and can even out over time.

Rolling resistance change due to a slid flat has a very small impact on overall rolling resistance and an insignificant impact on fuel mileage.

Radial tires are more durable and have a lower rolling resistance than bias ply tires.

New tires are more durable than retread tires.

AAR – Section F – Rule 82g – Slid Flat Criteria

Old Rule:

Tire replaced when flat spot removes a minimum of 4/32”of tread

New Rule:

Tires replaced when the flat spot tread depth is 2/32” or less (Aligns with DOT replacement criteria)

Damage – flat spot tread depth is 2/32” or less and remaining tread is 5/32” or more

Damage - Tires rotated 90 – 180 degrees where tires on the same dual (i.e. RIF, ROF) have adjacent flats spots which removed a minimum of 6/32” of tread and do not meet replacement criteria

Owners – flat spot tread depth is 2/32” or less and remaining tread is less than 5/32”

Rule Change Summary Review:

AAR – Section F – Rule 82g – Slid Flat Criteria

Example – Tires Not Requiring Replacement

AAR – Section F – Rule 82g – Slid Flat Criteria Example – Tire Not Requiring Replacement

AAR – Section F – Rule 82g – Slid Flat Criteria Example – Tires Requiring Replacement – Owner’s Responsibility (Slick Tread)

AAR – Section F – Rule 82g – Slid Flat Criteria Example – Tire Requiring Replacement - Damage

AAR – Section F – Rule 82g – Slid Flat Criteria Example – Tire Requiring Replacement - Damage

AAR – Section F – Rule 82g – Slid Flat Criteria Example – Tire Requiring Rotation - Damage

AAR Slid Flat Testing & Analysis Benefits: • DOT alignment relative to slid flat tire replacement

• Ability to rotate dual tires with matching slid flats

• Fair assignment of responsibility (owner vs handling carrier)

• Less tire replacements – removing supply chain costs • Ability to redirect mechanical resources to improve asset availability

• Smaller environmental impact relative to less tire disposal